This invention relates to a printed circuit board with SMD components electrically connected to the circuit board by means of a reflow soldering process. The invention also relates to an electrical apparatus including such a printed circuit board and to a method of manufacturing a printed circuit board.
SMD components are mounted on the surface of printed circuit boards (xe2x80x9cSurface Mounted Devicexe2x80x9d). In the assembly of the printed circuit board, soldering paste is first provided in a predetermined pattern on the printed circuit board by means of a silk-screening method. Subsequently, the SMD components are mounted on the printed circuit board and possibly fixed to the surface of the printed circuit board by means of a non-conducting adhesive, the component connections coming into contact at the predetermined positions with the soldering paste patterns printed on the printed circuit board. The components themselves and their connections are situated on the same side of the printed circuit board. Subsequently, the reflow soldering process (a flow soldering process) is performed. The solder provided on the printed circuit board is melted by way of a heat supply from an appropriate furnace, so that fixed electric soldering connections between the SMD components and the printed circuit board are formed.
Connection elements are required for realizing electric connections to other electric components, for example, other printed circuit boards or internal connections of electrical apparatuses. Known embodiments are connection pins or pin strips embedded in synthetic material blocks which, together with the SMD components, are mounted on the printed circuit board after the soldering paste has been provided. It is a drawback in this case that the synthetic material requires additional space on the printed circuit board and that additional costs are involved, while this synthetic material cannot be liquified at the high temperatures during the reflow soldering process. The additional costs are quite considerable, particularly in mass production. In alternative methods, separate connection elements (for example, connection pins) are manually soldered onto the printed circuit board after the reflow soldering process, which involves additional labor costs.
It is an object of the invention to provide a printed circuit board having connection elements which can be mounted at minimal cost.
This object is achieved in that the printed circuit board has one or more connection elements used for an electric p connection to other electric components, which connection elements are journaled in recesses of the printed circuit board and do not project to the exterior via the surface of the printed circuit board on which the SMD components are secured.
Mounting of the connection elements, particularly implemented as connection pins, may thus be integrated in the automated process of manufacturing the printed circuit board. The connection elements are arranged in the printed circuit board in such a way that the soldering paste can be provided between the connection elements and the printed circuit board by means of a silk-screening process. This can be particularly realized in that the connection elements do not project to the exterior via the surface of the printed circuit board on which the SMD components are fixed.
When the connection elements are arranged in a peripheral area of the printed circuit board, the printed circuit board may be implemented in a very simple way by recesses in the peripheral area for engaging and journaling the connection elements. Such recesses can be made by way of, for example, punching or milling processes. To ensure a fixed fit of the connection elements already before and during the soldering process, the connection elements are pressed into the recesses, which may be performed in an automated process.
The invention also relates to an electrical apparatus including a printed circuit board according to the invention. For example, the printed circuit board may be used in electrical apparatuses for consumer electronics. However, its field of application is not limited to such uses. The printed circuit board according to the invention is preferably used in mass-manufactured electrical apparatuses.
The invention also relates to a method of manufacturing a printed circuit board with SMD components which are electrically connected to the printed circuit board by means of a reflow soldering process, in which, prior to providing the soldering paste used for the reflow soldering process, one or more connection elements, used for an electric connection to other electric components, are arranged at the appropriate positions in the printed circuit board. Subsequently, the connection elements are connected to the printed circuit board by means of the reflow soldering process. The advantages which can be achieved by means of this manufacturing method are defined in the above-mentioned implementations.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.